From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from foss.arm.com (foss.arm.com [217.140.110.172]) by smtp.subspace.kernel.org (Postfix) with ESMTP id E5EF229ACFD; Thu, 20 Aug 2026 19:40:39 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=217.140.110.172 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1787254842; cv=none; b=FX4LPixqZpZJ4Mr/eTEhageAW/kVY+ddSsLdPFNNiV5oOvPCbRLkYOTH7vr3cIGOcQ7tP0wSaPdyAmVm0dE26MA1u9blyekrxE1BL+p2zqxpGTQYFWR7ziljCZmR0Ns9d+ZCIAnE3bmuxMdm9NKzTUNAXoK43IpeHTKc4WJstcM= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1787254842; c=relaxed/simple; bh=uMRo3I+EyfXXqmw4cBxiWSky9p9AXwXW6zcs9CuZKso=; h=From:Date:Subject:MIME-Version:Content-Type:Message-Id:References: In-Reply-To:To:Cc; b=T4bxp+urH3SJ08xEBMWLsXUIA+rUXY/T5uO4c85u4o03CTYs90l6njmR5cuR+srsehVwojqYeIL+UnYdm8RljTu6mMzQvgAQ0XtCPfBM/wMcajLWAu2+chKe1Sg8zNEjctm4xYCMSOQ0K6sQbR8oA0rQTzW5yzyPHHNbMIFXmG8= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=arm.com; spf=pass smtp.mailfrom=arm.com; dkim=pass (1024-bit key) header.d=arm.com header.i=@arm.com header.b=k40VweNT; arc=none smtp.client-ip=217.140.110.172 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=arm.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=arm.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=arm.com header.i=@arm.com header.b="k40VweNT" Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.121.207.14]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id 72F6C20E3; Thu, 20 Aug 2026 12:40:35 -0700 (PDT) Received: from e129823.arm.com (e129823.arm.com [10.2.213.3]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id BEA173F763; Thu, 20 Aug 2026 12:40:36 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=simple/simple; d=arm.com; s=foss; t=1787254839; bh=uMRo3I+EyfXXqmw4cBxiWSky9p9AXwXW6zcs9CuZKso=; h=From:Date:Subject:References:In-Reply-To:To:Cc:From; b=k40VweNT0NG3FjlkrTCZGQt7NG81uUFpQzD/ZEn+8bQX2IurfEzfA3aLh+Iqfdwit rVQ9lHzZg6bvqXF4vOIyWVQZWRIxpvPQKODvSf4B1Reho5a1G29PxEJHcbpqVnHvS5 cdr2y0f7YCyAY7jeeN45W2j9kYu7pLQp1MIjfM8Y= From: Yeoreum Yun Date: Thu, 20 Aug 2026 20:40:15 +0100 Subject: [PATCH 1/2] kselftest: mm: prevent random failure of huge page split for khugepaged Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 7bit Message-Id: <20260820-fix_split-v1-1-ab430c58c7cf@arm.com> References: <20260820-fix_split-v1-0-ab430c58c7cf@arm.com> In-Reply-To: <20260820-fix_split-v1-0-ab430c58c7cf@arm.com> To: Andrew Morton , David Hildenbrand , Lorenzo Stoakes , Zi Yan , Baolin Wang , "Liam R. Howlett" , Nico Pache , Ryan Roberts , Dev Jain , Barry Song , Lance Yang , Usama Arif , Vlastimil Babka , Mike Rapoport , Suren Baghdasaryan , Michal Hocko , Shuah Khan , Kevin Brodsky Cc: linux-mm@kvack.org, linux-kselftest@vger.kernel.org, linux-kernel@vger.kernel.org, Yeoreum Yun X-Mailer: b4 0.13.0 X-Developer-Signature: v=1; a=openpgp-sha256; l=2249; i=yeoreum.yun@arm.com; h=from:subject:message-id; bh=uMRo3I+EyfXXqmw4cBxiWSky9p9AXwXW6zcs9CuZKso=; b=owEB7QES/pANAwAKAW3Vw9FaxTEzAcsmYgBqh1gwFNiZL1JKhbXTdharWu6xO72tiOOQScaBM kX8t0XWnIiJAbMEAAEKAB0WIQQtg+CS3QUzuFh1pJ1t1cPRWsUxMwUCaodYMAAKCRBt1cPRWsUx MylyDACthWK3rDwGK6zCbh9WSTwdnNwTIofCM1WGv4e/TMI+PwoaYxSNF7LDRAUcCEZM9ttUPP+ nIJsAIjVVKNx13eQ1onh344xtr79CSMN6FD3b3fPUu3RudaWG3WU8F3q5WoRhB/yLJHeqW2DNls LnZE++AfWw5quokjFbqLlsx1+LCKg65PDlWdmQPquYRfH5Y9YPTb0OR73/QJOw6zgixaI8Up+TB vSHJamhtvvkleUUf7o5HsuQW6jY3tA0HXXngEzkVr9s9tZPs8wnKc4yECfDeGu+VN+CaMXs+e3s HiO+gNocF5Ybyls2EcwEA9hCZDQ9jPFT9pFzP2JPwRABKGxA29zod2BsQ/6ZPaaWjWvrhB6jJoM 97IqCIB4bvH3G1C8KiVhxJRjD47NBWpADf5671WNkQGdHV9CCWY9BvHebBMQyNpm3DTn6rJgpXI wecULLuSKPAnEapAkfzW4FjNF3LYeFhHl1AFudoanwgOWVHCUkXg6u3jAy7WmvT4us2n8= X-Developer-Key: i=yeoreum.yun@arm.com; a=openpgp; fpr=2D83E092DD0533B85875A49D6DD5C3D15AC53133 There're some random failure for split_huge_page_test when khugepaged collapses pages into pmd again which had split by the test. Prevent the khugepaged's collapses for split page by setting the mapped pmd-huge-page with MADV_NOHUGEPAGE before split. Reported-by: Kevin Brodsky Signed-off-by: Yeoreum Yun --- tools/testing/selftests/mm/split_huge_page_test.c | 11 +++++++++++ 1 file changed, 11 insertions(+) diff --git a/tools/testing/selftests/mm/split_huge_page_test.c b/tools/testing/selftests/mm/split_huge_page_test.c index 32b991472f744..99b45e5518199 100644 --- a/tools/testing/selftests/mm/split_huge_page_test.c +++ b/tools/testing/selftests/mm/split_huge_page_test.c @@ -303,6 +303,9 @@ static void verify_rss_anon_split_huge_page_all_zeroes(char *one_page, int nr_hp if (!rss_anon_before) ksft_exit_fail_msg("No RssAnon is allocated before split\n"); + /* Prevent khugepaged from collapsing the pages. */ + madvise(one_page, len, MADV_NOHUGEPAGE); + /* split all THPs */ write_debugfs(PID_FMT, getpid(), (uint64_t)one_page, (uint64_t)one_page + len, 0); @@ -350,6 +353,9 @@ static void split_pmd_thp_to_order(int order) if (!check_huge_anon(one_page, 4, pmd_pagesize)) ksft_exit_fail_msg("No THP is allocated\n"); + /* Prevent khugepaged from collapsing the pages. */ + madvise(one_page, len, MADV_NOHUGEPAGE); + /* split all THPs */ write_debugfs(PID_FMT, getpid(), (uint64_t)one_page, (uint64_t)one_page + len, order); @@ -436,6 +442,9 @@ static void split_pte_mapped_thp(void) goto out; } + /* Prevent khugepaged from collapsing the pages. */ + madvise(thp_area, thp_area_size, MADV_NOHUGEPAGE); + /* Split all THPs through the remapped pages. */ write_debugfs(PID_FMT, getpid(), (uint64_t)page_area, (uint64_t)page_area + page_area_size, 0); @@ -665,6 +674,8 @@ static int create_pagecache_thp_and_fd(const char *testfile, size_t fd_size, ksft_test_result_skip("Pagecache folio split skipped\n"); return -2; } + /* Prevent khugepaged from collapsing the pages. */ + madvise(*addr, fd_size, MADV_NOHUGEPAGE); return 0; err_out_close: close(*fd); -- 2.43.0